1. Field of the Invention
The present invention relates generally to a housing for a surveillance camera, and more particularly to a pressurizable housing for a surveillance camera having an improved pressure sealing and interior access arrangement.
2. Description of Related Art
Surveillance cameras are widely used for security and monitoring purposes. A protective housing often encloses a surveillance camera to protect the camera from damage by the elements, to prevent vandalism, to conceal the camera, and/or for aesthetic purposes. Such housings can be domed, shaped to generally match the camera contours, or otherwise configured. The camera and housing are typically mounted to a wall, ceiling or support structure, and electronically coupled to a power source and a remote monitoring and/or recording station.
It has been found advantageous in certain applications to pressurize the housing of a surveillance camera for improved protection against the elements. For example, a pressurized gas such as dry nitrogen can be introduced to a sealed housing to prevent the intrusion of moisture, dust, insects and other potential contaminants or debris. U.S. Pat. No. 5,852,754 to Schneider, which is incorporated herein by reference, discloses an example embodiment of a pressurized camera housing.
It is desirable that the interior of a camera housing be easily accessible for installation, service and maintenance purposes. Therefore, known housings typically permit partial disassembly or removal of structural components for access to the housing interior. In order to permit pressurization, known pressurized camera housings typically incorporate O-rings, gaskets, or other sealing elements to prevent pressure loss between their separable structural components. Each sealing point, however, presents a potential avenue for pressure loss and debris introduction. Therefore, it is desirable to maintain the number of sealing points at a minimum. The pressurized camera housing disclosed by U.S. Pat. No. 5,852,754 performs well in many applications. This housing, however, requires a rigid assembly plate, to which the lower dome and upper enclosure are separately sealed. The assembly plate and the necessity of separate seals for the lower dome and the upper enclosure contribute significantly to the expense of the housing, both in material costs and labor. The assembly plate also adds weight to the housing, which may render installation and maintenance more difficult than would optimally be desired. In addition, the assembly plate of this housing is typically supported by a mounting bracket, which supports the housing from the rear side thereof. In many instances, however, it is desirable to provide a top-mounting housing that is supported from above.
It has therefore been found that a need exists for an improved camera housing that is pressurizable, simple and economical in construction, aesthetically attractive, and durable in use. It is also desirable that the camera housing be lightweight and permit easy access to the interior thereof, while minimizing the number of sealing points necessary. It is also desirable to provide a camera housing that is readily adaptable for top-mounting. It is to the provision of a camera housing meeting these and other needs that the present invention is primarily directed.
The present invention provides an improved camera housing capable of maintaining a positive pressure gradient between its internal volume and the surroundings. The camera housing facilitates easy access to the interior thereof, and provides an efficient sealing arrangement. The camera housing advantageously eliminates the need for a rigid assembly plate, and instead provides a seal between the first and second housing shells. Alignment of the seal location with wall portions of the first and second housing shells
In one aspect, the present invention is a pressurizable camera housing including a first housing element having a transparent dome with a flange extending therefrom, a second housing element having a rim releasably coupled to the flange of the first housing element, and a first O-ring engaged between the flange of the first housing element and the rim of the second housing element. The housing preferably further includes a sealing plate engaged within an opening through the second housing element, whereby the first housing element, the second housing element, and the sealing plate define an interior chamber. The housing preferably further includes a second O-ring engaged between the sealing plate and the second housing element. A hermetic electrical coupling is preferably included for conducting an electrical signal between the interior chamber and an external element. The housing preferably also includes means for introducing a pressurized fluid into the interior chamber.
In another aspect, the present invention is a pressurizable camera housing including a first housing shell having a transparent portion, and a second housing shell removably attached to the first housing shell, whereby an airtight seal is provided between the first and second housing shells.
In another aspect, the present invention is a pressurizable housing including a first housing shell that is at least partially transparent; a second housing shell adapted to engage the first housing shell, whereby the first and second housing shells bound an interior chamber; and sealing means between the first and second housing shells. The housing preferably also includes means for introducing pressure to the interior chamber, and means for mounting a camera within the interior chamber.
These and other features and advantages of preferred forms of the present invention are described in greater detail herein with reference to preferred and example embodiments.